Process of treating sugar-cane.



rna nnrornrcn OF BOSTON, MASSACHUSETTS,

A CORPORATION OF NEW JERSEY.

= PROCESS OF TREATING SUGAR-CANE.

No Drawing.

To all whom it may concern Be it known that I,'TENNANT LEE, aciti-.

zen of the United States, residing at Dedham, in the county of Norfolkand State of Massachusetts, have invented certain new and usefulImprovements in Processes of Treating Sugar-Cane, of which the followmgis a specification. r

This invention is a process hav ng for its ob ect a more advantageous'ut1l1zat1on of ,so-called bagasse or megass? which terms are hereinsynonymously used to designate the moist woody residues from the millingof sugar-cane. v

agasse is at present commonly burned as fuel for steam generation.Usually the bagasse production of a cane'sugar factory is somewhat lessthan its total fuel requirements, rendering it necessary to supplementthe bagasse by other forms of fuel.

It has frequently been proposed to utilize the bagasse as paper stock,and many attempts to accomplish this have beenmade. Such utilizationhasfnot heretofore proven commercially practicable, partly on account ofthe comparatively low yield and inferior grade of paper obtained, andpartly on account of the necessity involved in all prior methods ofsubstituting for the bagasse other and more-expensive fuels, as wood,

gcoal or oil.

I cellent. commercial jected, and that present invention, exgrades ofpaper are obtained from the bagasse, Withsatisfactory yields from theraw material, and without excessive expenditure for other fuel.

The present invention is based on the following considerations :Ordinarymill-badelivered to the burners, contains approxlmately 50 per cent.- ofmoisture associated with a variety of plant tissues which are. notequally adapted for paper-making purposes. Furthermore, it is commonlybelieved that these tissues have been injured or impaired forpaper-making According to the purposes by the heavy crushing and millingoperations to which they have been subsuch. injury accounts.large-measure for the weakness and inferior quality of the paperheretofore produced from bagasse.

Careful studies of the actual condition of the plant tissues in thebagasse from a heavy nnlling-plant, located in the tropics, andcomprising a cane crusher and nine Specification of Letters Patent.

mak1ng purposes,

' is such that I selectedfiber Patented Oct. 5, 1915.

Application fil ed September 16, 1913. Serial No. 790,126.

rollg have now shown :that while such injury as is above referred to hasin fact been incurred by the fibers, this injury is, contrary toexpectations, very largely confined to the thick-walled ground tissuesadjacent the rind, and to the highly silicious' cells of the rinditself. Even aside from the im pairment of the fibers due to thecrushing and milling, the rind and adjacent tissues have proven to beill adapted for paperowing to their brittle character, their highsilica-content, their resistance to alkaline lyes, and the associa--tion therewith of coloring-matters.

The or pith, likewise paper stock, and

thin-walled ground tissue, constitutes a very inferior is largelydestroyed in the usual processes of digestion. v

y process contemplates such treatment of the moist bagasse as willresult in the separatlon therefrom of those fibers, or a certainproportion thereof, which are in I themselves best adapted forpaper-making,

and which have not been lmpaired in value for this purpose by thecrushing and milling operations. Such fi for convenience termed selectedfiber. The separation and separate recovery of the selected fiberinvolves a partial drying of the original moist bagasse, and suchtreatment of the partially dried material as will eliminate therefrom,as completely as may be practicable, the soft pith-cells on the onehand, and the hard rind and impaired heavy-walled, ground tissue on theother here are hereinafter hand. These rejected portions of the tissue,7

usually constituting more than 50 per cent. of the woody matter of theoriginal bagasse, are conveyed directly to the burners and utilizedforge eration of steam. While the weight, of pa 'ially dried materialthus available for fuel is materially less than the weight of thebagasse from which it was de rived, its fuel value per unit of weight ismaterially greater than that of the original moist bagasse,.-so that therequirements of the factory for other fuels are not excessivelyincreased. At the same time, the character and condition of the selectedfiber am able to prepare therefrom excellent grades of paper; and theshrinkage in the preparation of paper stock from this fiber is no longerexcessive, because the is substantially uniform in respect to the actionof the alkaline lye or other liquor used for digestion, by reason of itscomparative freedom both from the highly sensitive pith and from thehighly resistant rind. Hence this process overcomes each of the knowndisadvantages of the use of bagasse forpaper-making purposes, viz., theinferior grade of the paper, the heavy shrinkage of the stock, and thetotal loss of the fuel value of the bagasse. It is also advantageousthat the new process may be used in connection with existingmilling-plants by mere additions to the existing equipment.

The present process may be carried out as follows :The moist bagasse isdried, preferably by agitation in a current of highly heated gases ofcombustion, to a moisturecontent of 15 to 25 per cent, and is therebybrought to such condition-that those portions of the pith which stilladhere to the fibrous strips may be, to a' large degree, shaken free byimpact. or detached by a shredding or picking process. The degree towhich the drying is carried is chosen solely with reference to thefacility with which the component tissuesmay be separated. Satisfactoryresults as regards the detachment of the pith and the separation of theselected fiber from the pith and rind may be obtained by the use of aWilliams ulverizer, or other impact device, followed y screening by aseries of vibratory screens of varying mesh; or in general any device orseries of devices capable of detaching the pith and separating theselected fiber may 1 be employed, whether their use involves one or moreoperations. For. example, the separate recovery of the selected fibermay be accomplished by methods involving-the use of air flotation. Therejected fractions of the bagasse, which may be designated forconvenience the pith. and rind portions, are

conveyed directly to the burners, their'increased fuel value due to thepartial drying largely compensating the withdrawal of the selectedfiber. The selected fiber is preferably washed, usually by systematicdiffusion, and is then-digested for the preparation of paper stock. Thecondition of digestion are chosen with reference to the requirementsofthis substantially uniform selected fiber,

thereby avoiding the necessity which is inherent in processes utilizingthe harder fibers of the rind and. adjacent parts, of carrying out thedigestion under such drastic conditions that the more sensitive fibers,in-

cluding those herein referred to as selected fibers, are eitherdestroyed or their value greatly impaired. The following conditions havebeen successfully employed, it being understood that the invention isnot limited thereto :The selected fiber is digested for about eighthours under forty pounds steam pressure, in presence of caustic sodaequivalent to above fourteen per cent. by weight of the dry fiber. Theweak sugar liquors from the washing of the selected fiber are preferablyapplied to maceration between the mills whereby the sugar-content of theselected fiber is conserved, and the total yield of sugar iscorrespondingly increased.

1. The herein-described process of treating moist sugar-cane bagasse toprepare therefrom a fibrous concentrate suitable for paper-making, and afuel, which consists in drying the moistbagasse to'a condition suitablefor the-mechanical grading of the plant tissues, mechanicallydissociating said tissues and separating the harder and softer tissuesfrom the intermediate selected fiber suitable for paper-making.

2. In a process of utilizing moist bagasse from sugar-cane, the stepswhich consist in drying the bagasse to a condition suitable for themechanical grading of the plant tissues, mechanically dissociating saidtissues, separating the harder and softer tissues from the intermediateselected fiber, and digesting the selected fiber.

3. In a process of utilizing moist bagasse from sugar-cane, the stepswhich consist in drying the bagasse to a condition suitable for themechanical grading of the plant tissues, mechanically dissociating saidtissues, separating the harder and softer tissues from the intermediateselected fiber, washing the selected fiber, and digesting the washedfiber.

In testimony whereof I affix my signature in presence of two witnesses.

TENNANT LEE.

Witnesses J AS. H. BLAGKWOOD, G. P. TOWNSEND.

Corrections in Letters Patent No. 1,155,741;

specification requiring correction as follows:

8 It is hereby certified that in Letters Patent No. 1,155,741, grantedOctober 5, 1915 upon the application-of Tennant Lee, of Ded hamMassachusetts, for an I improvement Processes of Treating S11gar-Cane,err0rs abpeer in the printed dition readwond'itions; samepage, line 65, for the word abovev read about; and

that the said Letters Patent should' be read with these correctionstherein that."

the same met conformto' the record of the case in the PetentOtfic-Signed and sealed this Zndday 9f November, A. D., 1915, v .R. F.WHITEHEAD, I

[sEA Q] I I Commissioner of Patents Page 2, line 49, for the Word eon-

